A liquid crystal display device typified by a liquid crystal display panel, a liquid crystal display module and so forth utilizes optical anisotropy, dielectric anisotropy and so forth, which are possessed by a liquid crystal compound (in this invention the liquid crystal compound is used as a generic term for a compound having a liquid crystal phase such as a nematic phase or a smectic phase, and a compound having no liquid crystal phases but useful as a component of a liquid crystal composition). A variety of operating modes of this liquid crystal display device are known, such as a PC (phase change) mode, a TN (twisted nematic) mode, a STN (super twisted nematic) mode, a BTN (bistable twisted nematic) mode, a ECB (electrically controlled birefringence) mode, a OCB (optically compensated bend) mode, a IPS (in-plane switching) mode, a VA (vertical alignment) mode, a PSA (polymer sustained alignment).
In the operating mode, the ECB mode, the IPS mode, the VA mode and so forth utilize homeotropic orientation of liquid crystal molecules, and it is known that in particular the IPS mode and the VA mode are able to improve a limited viewing angle that is a disadvantage of a conventional display mode such as the TN mode or the STN mode.
A variety of liquid crystal compounds in which hydrogen on the benzene ring had been replaced by fluorine have conventionally been studied as a component of a liquid crystal composition having negative dielectric anisotropy, which can be used for liquid crystal display devices having these operating modes.
For example, the compounds (A) and (B), in which hydrogen on the benzene ring had been replaced by fluorine, were studied (see patent documents Nos. 1 and 2). However, these compounds did not have such a large negative dielectric anisotropy that satisfied market demand.
The compound (C) having a fluorine-substituted benzene was also studied (see patent document No. 3). However, this compound did not have such a large negative dielectric anisotropy that satisfied market demand.
The quarterphenyl compound (D) having a fluorine-substituted benzene was also studied (see patent document No. 4). However, this compound had a quite high melting point and a poor compatibility. The compound did not have such a large negative dielectric anisotropy that satisfied market demand.
The compound (E) having an ethylene bonding group and two fluorine-substituted benzene was also studied (see patent document No. 5). However, this compound (E) had a high melting point and a poor compatibility. The compound did not have such a large negative dielectric anisotropy that satisfied market demand.
